Panamanian golden frog
Description Despite its common name, the Panamanian golden frog is a true toad. It was previously considered a subspecies of Atelopus varius but is now classified as a separate species.34 The skin colour of the golden frogs ranges from light yellow-green to bright gold, with some individuals exhibiting black spots on their back and legs. Female golden frogs are generally larger than males; females typically range from 45 millimetres (1.8 in) to 63 millimetres (2.5 in) in length and 4 grams (0.14 oz) 15 grams (0.53 oz) in weight, with males between 35 millimetres (1.4 in) and 48 millimetres (1.9 in) in length and 3 grams (0.11 oz) and 12 grams (0.42 oz) in weight.5 Toxicity Like some other frogs and toads, the golden frog is capable of secreting poison to help protect itself from predators. In the case of the golden frog, this is a water-soluble neurotoxin called zetekitoxin.6 The skin of A. zeteki is highly toxic, containing around 500 mouse units of toxin. A mouse unit of toxin is defined at the amount of toxin it takes to kill a 20 gram mouse. The toxin is different from the toxin in other poisonous amphibians which is evident in its extremely high toxicity which differentiates it from both toxins from Dendrobates pumilio. Due to the danger of testing the poison in human it has been done on mice. With large doses of the poison death can occur in as little as 2 minutes and with smaller doses it can be delayed for 20 or 30 minutes. Death is preceded by clonic convulsions until the functions of the circulatory and respiratory systems cease..7 Distribution Golden frogs are endemic to Panama, living close to mountain streams on the eastern side of the Tabasará mountain range in the Coclé and Panamá provinces.2 The range of the golden frogs previously extended as far east as the town of El Copé in western Coclé Province before the onset of the fungal disease chytridiomycosis, which caused the El Copé population to rapidly collapse in 2004.2 Individuals are kept in captive breeding programmes in more than 50 institutions across North America and Panama.89 Ecology The life span of the golden frog is 12 years.5 This toad is unusual in that it communicates by a form of semaphore, waving at rivals and prospective mates, in addition to the sounds more usual among frogs. This adaptation is thought to have evolved in the golden frog because of the noise of the fast-moving streams which formed its natural habitat.10 The male tends to stay near the streams where breeding occurs, while in the non-breeding season the female retreats into the forests. The male uses a soft call to entice prospective mates, then grabs the female and hangs on when she crosses his path. If she is receptive, she will tolerate amplexus; if not she will attempt to buck him off by arching her spine.[citation needed] Amplexus can last from a few days to a couple of months, with ovipositioning usually taking place in a shallow stream.6 Life history The development of A. Zeteki can be divided into four stages; larvae or tadpole, juvenile, subadult and adult. During the larvae stage they emerge from their eggs after 2 to 10 days of development. They are entirely aquatic creatures at this stage and are found in waters with a temperature range from 20.4 C to 21.3 C and with depths of 5 to 35 cm. After emerging they mostly spend time resting in shallow pools below cascades. This behavior is similar to A. certus. Wherever water pools in a stream they are likely to be found, as long was connected to moving channels, The tadpoles however do not venture into the moving channels. Visually the larvae is characterized as gastromyzophorous. They are typically around 5.8 mm in length and 4.3 mm in width. Their snouts are rounded as well as their tails. The longest claudal fins on their tails are about three fifths the length of the tail itself. Their mouths are large and ventral surrounded by labia which form an unbroken oral disc about 3.6 mm wide. The posterior lip has no papillae but other lips are lined with single rows of small blunt papillae. They are colored from dark brown to black dorsally with golden flecks on their bodies. They develop this black and gold coloration as melanin floods their dermal layers, giving the larvae protection from the sun. When metamorphosing they loose their golden flecks and they are replaced with dark green ones.1 The tadpoles feast on algae and spend 6 to 7 months developing and growing.5 The juveniles of this species are amphibious at this stage but have a far smaller range than subadults and adults. Normally the juveniles are not found more than 2 meters from their stream and recently metamorphosed juveniles are more likely to be found next to the stream pools teeming with tadpoles.1 Like their adult counterparts the juveniles go to higher elevations and recede into trees to prevent predation, however, due to their small size the juveniles are not able to cover as much elevation and climb as highly into trees and shrubbery.11 At the onset of heavy and consistent rains the juveniles flee from the open streamside, which are normally where the grown adult males, who are very territorial are known to roam. Territorial behaviors by adult males could be initiated by these rains. Visually the juvenile has snout to vent lengths ranging from 8.4 to 17.1 mm. Their dorsal coloration is a deep and vivid green which matches the color of the moss that grows on the rocks in and around the streams of their habitat. There are also dark brown to black dorsal markings. Some of the juveniles are also known to have small dark markings on their digits. Their venter or abdomen is either white or goldenrod yellow occasionally with dark markings that do not match the ground color.1 The subadults of this species have full ranges but they are sometimes found near adult males which is noteworthy due to the fact that males of this species are fairly solitary and combative in the presence of other males. The subadult is about 28.3 mm long and weights about 1.1 gram. They are more greenish in color which more closely resembles the color of the metamorphic juvenile than the brilliant and sometimes spotted golden color of the adult. The patterning of subadults is significantly more darker than the adults.1 Behavior The golden frog appears to socialize with other amphibians using sounds from the throat and hand-waving, like the semaphore motion used in courtship. The movements may be friendly or aggressive warnings.10 It is an "earless" species of frog, meaning it lacks an eardrum also called a tympanic middle ear. This however, does not inhibit its ability to communicate with other members of its species through throat sounds like other frogs do. Despite lacking an eardrum, researchers found that the "earless" frog responds to vocalizations produced by members of its own species. The male frog responds to a pulsed vocalization, characterized by lower frequencies followed by higher frequencies and so on, by exhibiting antagonistic behaviors such as turning to face the source of the sound and producing a pulsed vocalization in response. The pulsed call is used to demonstrate male position during combative situations. Like the frog's cousin Atelopus varius it is very territorial living in the same site most of its life. As a result of this site fidelity it will not hesitate to vocalize when another male frog encroaches on its territory. If this is not enough to get the intruder away the frog is not hesitant to defend its territory through aggressive behavior.12 The Panamanian Golden Frog apart from recognizing sounds, is also able to locate the origin of a sound. This means that the Frog is capable of directional hearing. In all other species of frog the role of the eardrum is to pinpoint the direction of sound. Due to the very small size of the Panamanian Golden Frog it is difficult to imagine another system of hearing that does not involve an eardrum apparatus.12 When the frog is encountered by a predator it often will wave and lift its foot at the predator to call attention to its stunning and beautiful coloring. This stunning coloring is a warning of its toxicity, which is enough to make a predator no longer consider the frog as a meal. If the predator continues to approach undeterred by the frogs warnings about its toxicity, the foot waiving, often accompanied with vocalizations will continue and increase in frequency and volume.12 It's toxicity is not a fool-proof method of protection however because some animals like Liophis epinephalus are able to metabolize the frogs poison. Ways to ward off predators and prevent predation are different in their diurnal habits versus their nocturnal ones especially because the poison alone will not ward off every predator. Adult males, who are active on the ground during the day recede into the trees and perch there at night. This is most likely a defense mechanism. If the predator is approaching at night the frog cannot rely on a visual strategy for fleeing. They perch on trees because it gives them the advantage of hearing approaching predators or feeling their weight on the tree branch. The noise and tactile advantages of climbing a tree are better than the advantages of burrowing in the ground.11 Conservation The species was filmed for the last time in the wild in 2007 by the BBC Natural History Unit for the series Life in Cold Blood byDavid Attenborough. The remaining few specimens were taken into captivity and the location of filming was kept secret to protect them from potential poachers. Populations of amphibians, including the golden frog, suffered major declines possibly due to the fungal infectionchytridiomycosis. The infection is caused by an invasive fungal pathogen that reached El Valle, the home of the Panamanian golden frog in 2006.13 Additional factors, such as habitat loss and pollution, may have also played a role.6 Although captive populations seem to thrive well, reintroducing them to an area will not stop the threat of chytridiomycosis. There are no current remedies to prevent, or any ways to control, the disease in the wild, but efforts are being made. There was one attempt to prevent a wide variety of frogs from the disease, by using bacteria known as Janthinobacterium lividium that produces a chemical against the infections; however the skin of the Gold frogs was unsuitable for the bacterium used.14The San Diego zoo started a conservation effort and received their first frogs in 2003. Since then, they have been able to successfully breed 500 individuals in captivity but will not release then into the wild until the fungal disease is less of a threat. The San Diego zoo also sends money to Panama to keep up the conservation effort in the frogs' native country.5 The temperature at which these amphibians keep may be in correlation with the infection of chytridiomycosis . It can be seen that the fungus is more prevalent in colder conditions.15 If there is a cold period, the behavior and immunity of the frogs may change around the same time more spores are released. When these frogs are infected with the fungus, their body temperatures rise to fight off the fungus. However, even if the infection leaves the frog and body temperature returns to previous normal levels, the infection can reemerge.16 Not only do these frogs face the threat of the fungal disease but they also are threatened by the development of society. As trees are cleared for housing and urbanization, the habitat of A. zeteki is destroyed. Other threats include the encroachment agriculture, pollution, pet trade, and aquaculture.2 "Project Golden Frog" is a conservation project involving scientific, educational, and zoological institutions in the Republic of Panama and the United States. The intended outcomes of this project include greater understanding of the golden frog, coordinated conservation effort by governmental agencies and non-governmental organizations, heightened awareness of current global amphibian declines, greater respect for wildlife among Panamanians and global citizens, and greater land preservation for threatened and endangered species throughout the world. This organization will use education, field studies, producing offspring through the already captive toads, and offering financial support to help preserve these toads.17 There have been two significant efforts to save these frogs. One being Amphibian Recovery Conservation Coalition (ARCC)which started in 2004. The organization exported the endangered amphibians to the USA believing it was a better environment for the endangered species. In 2005, the Houston Zoo established the El Valle Amphibian Conservation Center (EVACC) in Panama so that the endangered frogs could have protected facilities in their native country. EVACC has become a tourist attraction and the populations of the housed species are watched closely by researchers.18 In culture The Panamanian golden frog is something of a national symbol, appearing on state lottery tickets and in local mythology. It is thought that when the toad dies it turns to gold. It is believed that the toad brings good luck to those fortunate enough to see it.8 In 2010, the Panamanian government passed legislation recognizing August 14 as National Golden Frog Day. The main celebration event is marked annually by a parade in the streets of El Valle de Anton, and a display of golden frogs at the El Valle Amphibian Conservation Center in the El Nispero Zoo, El Valle.19 The highly toxic skin of the frog has also been used for centuries by the native people of the Panamanian forests for arrow poison.7 *